Buildings are generally constructed with floors, walls, ceilings, or roofs made of beams and panels which overlie or cover the beams. A problem which is encountered in constructing such buildings is the frequent development of squeaks.
In many structures, floors are constructed by installing a series of narrow joists--either metal or wooden--to provide support, and then placing panels of plywood or similar material on top of these. In this type of construction, squeaks often develop where a gap between the joist and the plywood permits the plywood to flex up and down as a person walks across the floor. Because it is usually necessary to remove carpeting and/or a ceiling to get at the source of the problem, repairing such squeaks is usually very expensive.
The conventional measure which has been adopted to combat this problem has been to glue the panels of plywood to the joists. This technique has been marked by only very modest success. For example, in the case of wooden floor joists, as the wood dries out, the warpage frequently becomes so great that the glue line simply breaks and the glue therefore becomes ineffective. Also, because such glues set up within a limited period of time, construction workers must place the panels on the joists almost immediately after the glue has been dispensed, which interferes with flexibility in managing the construction tasks of the projects. Furthermore, in very hot or cold climates, the glue tends to set up quickly, which aggravates this problem. Also, most such glues cannot be used when it is raining. Finally, when the panels are slid into place along the tops of the joists the glue is often scraped off, leaving bare spots where no glue is left to form a bond, making this conventional technique even less effective.
Accordingly, there exists a need for a method of constructing floors which effectively eliminates the development of squeaks. Furthermore, there is a need for such a method which is economical and convenient to practice, and which can be used in a wide range of environmental conditions.
Metal wall studs, floor joists and ceiling rafters, collectively referred to below as metal beams, offer builders and owners many significant economic and other advantages over traditional wooden beams (e.g., 2.times.4's, 2.times.10's, etc.). For example, such metal beams tend to be stronger and more resistant to deterioration. As a result, construction using metal beams is becoming increasingly common in both residential and commercial building.
Despite the inherent advantages which metal beams offer, metal construction has exhibited a number of drawbacks in practice. In particular, because the metal beams are highly thermally conductive, they tend to conduct heat away from the siding, flooring, sheet rock, or other panel covering much faster than would corresponding wooden beams; for example, the thermal conductivity of typical steel studs and other metal beams is about 320 btu/ft.sup.2 /hr/.degree. F., as compared to a typical figure of about 120-140 btu/ft.sup.2 /hr/.degree. F. for wood. As a result, "cold spots" are formed on the outer surface of the wail or floor covering, usually in the form of a series of spaced apart lines or bands which correspond to the arrangement of the underlying metallic beams comprising the metal framing. This tendency to conduct heat away from the wall or floor covering is increased by the normal practice of securing the materials together with metal fasteners (for example, screws).
Several additional problems stem from the high thermal conductivity of structures made using metal beams. Firstly, the cold spots cause condensation to form on the panel surface of the structure's exterior; this can often be observed as a series of vertical bands along the side of the structure. This leads to accelerated deterioration of paint or other finishes in these areas, and, also, (especially in cooler climates) fosters the growth of mildew which is both unsightly and difficult to eradicate. In addition, the moisture tends to be drawn into the panel along the metal beam, and will sometimes actually migrate along the metal beam into adjacent wooden supports, resulting in rot problems and, after prolonged exposure to moisture, the metal beams may rust.
Another problem which may develop from the thermal conductivity of metal studs, joists, and rafters is that the thermal integrity of the structure may be severely compromised. Specifically, the metal studs may conduct heat away from the interior of the house and out through panel walls, greatly reducing the house's energy efficiency.
Some attempts have been made to deal with the problems described above by using a metal foil which covers the inner surface of the wall or floor covering. Unfortunately, possibly owing to thermal conductivity of the foil material itself, this solution has generally proven ineffective, and in some cases appears to have actually aggravated the problem, especially by tending to draw moisture more rapidly into the wall. In addition, the foil and the beams generally are made of dissimilar metals. This dissimilarity causes electrolysis to occur between the metal beams and the metal foil, which in turn weakens the metal beam over time. Finally, the cost of the foil material renders this approach prohibitively expensive.
As a result, there exists a need for an effective and economical solution to the problems which are posed by the thermal conductivity of metal frame construction, as these have been described above.